Immunoassays for the detection of human carcinoma associated antigens and assays needed to support the clinical use of monoclonal antibodies have been developed. These assays are being used to examine body fluids, such as serum, ascities, and pleural effusions for the presence of tumor associated antigens. A competitive radioimmunoassays (RIA) has been developed to detect a tumor associated glycoprotein (TAG-72) identified by MAb B72.3. The competitive RIA and a second RIA, a double determinant immunoassay, detecting the same antigen, have been used to examine sera from patients with colorectal carcinomas, and other malignancies as well as normal sera. A mean of approximately 2 units/ml of TAG-72 was found in normal sera. Approximately 60% of patients with colorectal carcinomas have elevated (greater than 10 U/ml) levels of TAG-72 in their serum. Comparison of TAG-72 levels in sera with assays to detect other antigens also recognized by monoclonal antibodies clearly demonstrated that TAG-72 is different from the other antigens, and that TAG-72 can be found in some sera where no antigen is detected by the commercially available RIAs. Immunoassays are being developed to support clinical studies for evaluating the efficacy of MAbs to detect carcinomas as well as deliver therapeutic agents. Assays for the detection of circulating immune complexes, both antigen-antibody and antibody- antibody complexes, using high-performance liquid chromatography have been developed. Assays for the evaluation of the immunoreactivity and form of the injected MAb B72.3, as well as assays to examine the development of human anti-mouse antibodies have been developed.